“Radioactive substance visualization cameras” are known which visualize states of distribution of radioactive substances. The radioactive substance visualization camera is equipped with a cooling device and a sensor module. The cooling device cools the sensor module. While being cooled at a predetermined temperature or lower, the sensor module measures radiation data which shows a state of distribution of radioactive substances.
PTL 1 discloses a radiation detector which measures radiation including X-rays and gamma rays. This radiation detector achieves an improved signal-noise ratio by cooling a semiconductor radiation detecting element by means of an electronic cooling element.